LeetCode - Merge K Sorted Lists

Merge k sorted linked lists and return it as one sorted list. Analyze and describe its complexity.

Example:

Input:
[
  1->4->5,
  1->3->4,
  2->6
]
Output: 1->1->2->3->4->4->5->6

Java Solution:

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
class Solution {
    public ListNode mergeKLists(ListNode[] lists) {
        PriorityQueue<Integer> minHeap = new PriorityQueue<>();
        for(ListNode head : lists){
            while(head !=null){
            minHeap.add(head.val);
            head = head.next;
        }
        }
            ListNode dummy = new ListNode(-1);
            ListNode result = dummy;
            while(!minHeap.isEmpty()){
                result.next = new ListNode(minHeap.remove());
                result = result.next;
            }
            return dummy.next;
    }
}